CN116396037A - Lime stabilized iron tailing pavement subbase layer material for urban road and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of road pavement subbase materials and industrial solid waste treatment, and in particular relates to an urban road lime stabilized iron tailing pavement subbase material and a preparation method thereof, wherein the subbase material comprises the following components in parts by weight: 100 parts of iron tailings; lime 5-7 parts; 9-15 parts of water. The cured material prepared by the invention has higher compressive strength, meets the strength requirement of the lime-stabilized pavement subbase layer of the road, and has good thermal shrinkage resistance; the iron tailings are used as the base layer raw material of the road pavement, so that the problem of environmental pollution caused by the accumulation of a large amount of iron tailings is effectively solved, and good environmental benefits are achieved; the invention effectively solves the problem of shortage of sand and stone materials in road construction, reduces road construction cost and has good economic benefit.

Description

Lime-stabilized iron tailings pavement subbase material and preparation method for urban roads

technical field

The invention belongs to the technical field of road pavement subbase material and industrial solid waste treatment, and in particular relates to a lime-stabilized iron tailings pavement subbase material for urban roads and a preparation method thereof.

Background technique

Iron tailings are the waste solid materials with the lowest content of target components after the original iron ore has been sorted in the beneficiation process. It is generally in the form of fine powder. At present, its common treatment method is to store it in the tailings pond . However, this method of stockpiling iron tailings in the tailings pool has gradually revealed its various disadvantages in recent years. From an economic point of view, the stockpiling of iron tailings makes the factory need to bear additional land acquisition fees, transportation fees, and landfill fees. Increased production costs; on the other hand, this landfill disposal method not only needs to occupy a large amount of land resources, but also easily causes environmental pollution and safety problems, and new pollutants may be formed during the deposition of iron tailings. All indications are that the method of placing iron tailings in tailings ponds is an inefficient, non-environmental and non-economic treatment.

Road engineering has the characteristics of wide coverage and large amount of construction materials. Its huge consumption of earthwork and sandstone has caused huge environmental pressure on some sandstone origins, and even excessive mining has occurred, which has caused serious damage to the local ecological environment. caused huge damage. Therefore, if a suitable method can be found to apply iron tailings to road construction, it can not only solve various problems caused by the large accumulation of iron tailings, but also meet the huge demand for road construction materials and reduce road construction costs. , to achieve double benefits of ecology and economy.

At present, there are many studies on the application of iron tailings in road engineering, such as:

Patent CN109020338A discloses a method for designing cement-stabilized iron-like tailings base material. This method determines the optimal design parameters of the base material by measuring the 7d unconfined compressive strength of each group of tests in the star point design test table and fitting the ternary quadratic equation. In this method, the amount of iron tailings used in the base layer is determined to be 5%-30%, and the amount is limited.

Patent CN114292064A discloses a cement-stabilized iron tailings pavement semi-rigid base. In this patent, coarse-grained iron tailings waste rock, fine-grained iron tailings waste rock, and iron tailings are graded and designed, and finally stabilized with cement to prepare a cement-stabilized iron tailings pavement semi-rigid base. The particle size requirements of iron tailings mentioned in the patent are relatively large, which is not applicable to iron tailings with a high particle size content of less than 0.075mm.

Patent CN104152148A discloses a method for preparing pavement base material by stabilizing iron tailings with a novel soil curing agent. In the method, cement, crushed stone, iron tailings, new soil curing agent and polypropylene fiber are mixed to obtain the pavement base material. However, strong corrosive reagents such as sulfuric acid need to be used in the preparation process of the novel soil curing agent, which is not conducive to construction safety; and the curing agent becomes acidic, which has a certain impact on the strength growth of cement-based materials.

At present, although the research on the application of iron tailings to roads has achieved certain results, there are few studies on iron tailings with a particle size of less than 0.075mm and a content higher than 50%, and the utilization rate of iron tailings is insufficient.

Contents of the invention

The purpose of the present invention is to provide an iron tailings mixture that can efficiently utilize fine-grained iron tailings, meet the specification requirements, and can greatly reduce the cost of the mixture for urban road pavement subbases.

The technical solution adopted by the present invention to solve the technical problems is: a lime-stabilized iron tailings pavement subbase material for urban roads, the subbase material comprising the following components by mass: 100 parts of iron tailings; 5-5 parts of lime 7 parts; 9-15 parts of water.

Also provided is a preparation method of lime-stabilized iron tailings pavement subbase material for urban roads, comprising the following steps:

Step S1, after fully mixing the iron tailings and lime weighed according to the mass ratio, carry out a compaction test, and measure the _optimum moisture content MCjia and the maximum dry density _ρmax ;

Step S2, measuring the moisture content MC ₀ of the iron tailings, then weighing the iron tailings and lime in proportion, and mixing them evenly to obtain a mixture;

Step S3, increase the _optimal moisture content MC by 1-2 percentage points _as the preset moisture content MC of the mixture, calculate the amount of water added and weigh it;

Step S4, add 80%-90% of the weighed water into the mixture, seal it with a plastic film after fully stirring, and keep the mixture for more than 12 hours;

Step S5, after the stuffing is finished, the remaining water is added to the mixture for secondary mixing to finally obtain the required lime-stabilized iron tailings pavement subbase material for urban roads.

As a further preference of the present invention, the maximum particle size of the iron tailings is not greater than 4.75mm, the mass fraction of particles with a particle size below 0.075mm is greater than 60%, the plasticity index is 17-19, and the organic matter content is lower than 5%.

As a further preference of the present invention, the contents of various minerals in the iron tailings are dolomite (CaMg(CO ₃ ) ₂ ) 18%-22%, siderite (FeCO ₃ ) 18%-22%, quartz (SiO ₂ ) 15%-16%, calcite (CaCO ₃ ) 12%-13%, hematite (Fe ₂ O ₃ ) 11%-12%, kaolinite (Al ₄ [Si ₄ O ₁₀ ](OH) ₈ ) 9%-10%, muscovite (KAl ₂ [AlSi ₃ 0 ₁₀ ](OH) ₂ ) 8%-9% and pyrite (FeS ₂ ) 2%-3%.

As a further preference of the present invention, the leaching concentration of each heavy metal in the iron tailings is less than 26.77 μg/L for copper, less than 61.61 μg/L for barium, less than 2.28 μg/L for chromium, less than 2.28 μg/L for cadmium, and less than 2.28 μg/L for lead. The element is less than 0.20μg/L.

As a further preference of the present invention, the type of pavement for which the subbase material is applied is an urban road pavement.

As a further preference of the present invention, the layer where the subbase material is applied is a pavement subbase.

As a further preference of the present invention, the lime in the base course material is quicklime, and the grade is grade II ash and above.

Through the above technical solutions, compared with the prior art, the present invention has the following beneficial effects:

1, the present invention adopts unslaked lime as binding material, and ^the Ca that dissociates in the lime Can be adsorbed on the surface of soil particles, reduce the negative charge on its surface, make fine particles condense into larger aggregates under the effect of van der Waals force, thereby The soil particles are flocculated to form crystalline calcium hydroxide, calcium carbonate, hydrous silicon, and calcium aluminate cement. During the crystallization process of the cement, the stiffness, strength and stability of the material are continuously increased.

2. The present invention uses iron tailings to completely replace the clay and sand in the traditional formula, efficiently utilizes fine-grained iron tailings, effectively avoids the pollution of the environment caused by the accumulation of iron tailings, and also solves the problem of high-quality The problem of shortage of road construction resources reduces the mining of natural gravel, which has good environmental benefits.

3. From an economic point of view, iron tailings are waste solid materials produced in beneficiation operations, and the cost of road construction is basically zero except for transportation costs, which can effectively reduce the cost of road subbases and have good economic benefits.

4. Compared with the traditional lime-stabilized clay, the lime-stabilized iron tailings material for urban road pavement subbase proposed by the present invention has higher unconfined compressive strength, smaller temperature shrinkage, and higher strength and Resistance to temperature shrinkage.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is the preparation flowchart of embodiment urban road pavement subbase course with lime-stabilized iron tailings material;

Fig. 2 is the unconfined compressive test figure in embodiment 1;

Fig. 3 is the compressive strength curve chart of embodiment 2 and comparative examples 5-7 with age;

Fig. 4 is a diagram showing the variation of the temperature shrinkage coefficient with temperature in Example 3 and Comparative Examples 9-10.

Detailed ways

The present invention is described in further detail now in conjunction with accompanying drawing. These drawings are all simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, so they only show the configurations related to the present invention.

In the description of the present invention, it should be understood that the orientations or positional relationships indicated by the terms "left side", "right side", "upper", "lower" are based on the orientations or positional relationships shown in the accompanying drawings, and are only For the purpose of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, "first", "second" and the like do not represent components importance, and therefore should not be construed as limiting the invention. The specific dimensions used in this embodiment are only for illustrating the technical solution, and do not limit the protection scope of the present invention.

The iron tailings used in this application are selected from the iron tailings in the Liangtang tailings pond in Nanjing, collected on site and sealed up.

Example 1

The present embodiment provides a preferred embodiment, a lime-stabilized iron tailings pavement subbase material for urban roads, comprising the following components by mass: 100 parts of iron tailings; 6 parts of lime; 9-15 parts of water; preparation The method includes the following steps:

Step S1, after fully mixing the iron tailings and lime weighed according to the mass ratio, carry out a compaction test, the _best moisture content MC is measured to be 10.8%, and the maximum dry density _ρmax is 2.42g/cm ³ ;

Step S2, measure the moisture content _MC0 of the iron tailings to be 7.1%, then weigh the iron tailings and lime in proportion, and mix them uniformly to obtain a mixture;

Step S3, increase the _optimal moisture content MC by 1.5 percentage points _as the preset moisture content MC of the mixture, that is, 12.3% is used as the final moisture content of the mixture to calculate the amount of water added, and weigh the water according to the calculated amount of water added good;

Step S4, add 90% of the weighed water into the mixture, seal it with a plastic film after fully stirring, and keep the mixture for more than 12 hours;

Step S5, after the stuffing is finished, the remaining water is added to the mixture for secondary mixing to finally obtain the required lime-stabilized iron tailings pavement subbase material for urban roads.

Comparative example 1:

The difference from Example 1 is that no lime is added in Comparative Example 1, and the rest are the same as Example 1, and the required materials are prepared in the same way.

Comparative example 2:

The difference from Example 1 is that 2 parts of lime are added in Comparative Example 2, and the rest are the same as in Example 1, and the required materials are prepared according to the same method.

Comparative example 3:

The difference from Example 1 is that 10 parts of lime is added in Comparative Example 3, and the rest are the same as Example 1, and the required materials are prepared according to the same method.

Comparative example 4:

The difference from Example 1 is that no iron tailings were added in Comparative Example 3, and traditional road clay was used to replace it. The rest was the same as Example 1, and the required materials were prepared according to the same method.

With the material in embodiment 1 and comparative example 1-3, use universal press according to the unconfined compressive strength of inorganic binder stable material in " road engineering inorganic binder stable material test procedure " (JTG E51-2009) According to the test requirements, prepare cylindrical specimens of Ф50mm×50mm, at least 6 for each group; after the preparation is completed, seal them and put them in a curing box for curing (curing temperature is 20°C, curing humidity is above 95%), after 6 days of curing Take it out, put it in water and soak it for one day, wipe off the moisture on the surface of the specimen after completion, and test the compressive strength of the specimen with a pavement strength meter. Please refer to attached drawings 1 and 2 for details of preparation and testing. The test results are shown in Table 1:

Table 1:

In Comparative Example 1, during the immersion process of health preservation, the specimen gradually loosened. After the immersion, the specimen was completely out of shape and could not be tested. From the test results, it can be seen that the difference in the amount of lime has a great influence on the unconfined compression resistance of the final material. The strength has a significant impact, and generally shows a trend of first increasing and then decreasing with the increase of lime content. When the ratio of iron tailings:lime is 100:6, the strength peaks, and the unconfined compressive strength meets the requirements of the urban road subbase. Requirements for material strength; Comparing Example 1 with Comparative Example 4, it can be seen that in the case of adding the same amount of lime, compared with traditional lime-stabilized clay for roads, lime-stabilized iron tailings have higher unconfined resistance. compressive strength.

Example 2:

The dosage and steps of the prepared materials in Example 2 are the same as in Example 1, the difference is that after the test pieces are prepared, they are divided into 5 groups, each group has at least 6 test pieces, and they are kept healthy for 6d, 13d, 27d, and 59d respectively. , Take it out after 89 days, take it out after soaking in water for one day, wipe off the moisture on the surface of the specimen, and test its unconfined compressive strength.

Comparative example 5:

Different from Example 2, Comparative Example 5 does not add lime.

Comparative example 6:

Different from Example 2, Comparative Example 6 added 4 parts of lime.

Comparative example 7:

The difference from Example 2 is that no iron tailings were added in Comparative Example 8, and traditional road clay was used to replace it.

Comparative example 5-7 is tested by the test method described in embodiment 2, obtains test result as shown in table 2:

Table 2:

The compressive strength curves of various materials are shown in Figure 3. It can be seen from Table 2 that the addition of lime significantly improves the unconfined compressive strength of the mixture at various ages, and its strength increases with age Continuously growing, when the iron tailings: lime is 100:6, the unconfined compressive strength of the mixture is the highest; Comparing Example 2 with Comparative Example 7, it can be seen that in the case of adding an equal amount of lime , compared with traditional lime-stabilized clay for roads, lime-stabilized iron tailings have higher unconfined compressive strength at all ages.

Example 3:

The consumption and steps of embodiment 3 preparation material are all identical with embodiment 1, and difference is that its material is according to the temperature shrinkage of inorganic binder stable material in " Highway Engineering Inorganic Binder Stable Material Test Procedure " (JTG E51-2009) According to the requirements of the test, prepare a cuboid specimen of 200mm×50mm×50mm, seal it and put it into a standard curing room (curing temperature 20 degrees, relative humidity above 95%) for curing. After curing for six days, the test piece was taken out, immersed in water, and the test piece was taken out after 24 hours. After that, put the test piece in an oven, dry it to constant weight, cool it at room temperature, and put it into a shrink box for testing. The test results are evaluated by the temperature shrinkage coefficient, which refers to the linear shrinkage of the material under changing unit temperature. The specific calculation method is as follows:

Among them, β _ij is the average temperature shrinkage coefficient of the material during the temperature ij change; Δ∈ _ij is the linear strain of the material during the temperature ij; Δt _ij is the temperature difference between the temperatures ij.

Comparative example 8:

Different from Example 3, Comparative Example 9 added 4 parts of lime.

Comparative example 9

The difference from Example 3 is that no iron tailings were added in Comparative Example 8, and traditional road clay was used to replace it.

Comparative example 9-10 is tested by the test method described in embodiment 3, and the results obtained are as shown in table 3:

table 3:

The temperature shrinkage coefficient of each material as a function of temperature is shown in Figure 4. It can be found that the appropriate increase in lime content reduces the temperature shrinkage coefficient of the material; compared with the traditional lime-stabilized clay for roads, lime-stabilized iron tailings have more Good resistance to temperature shrinkage.

Those skilled in the art can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. It should also be understood that terms such as those defined in commonly used dictionaries should be understood to have a meaning consistent with the meaning in the context of the prior art, and unless defined as herein, are not to be interpreted in an idealized or overly formal sense explain.

The meaning of "and/or" in this application means that each exists alone or both exist simultaneously.

The meaning of "connection" in this application may be a direct connection between components or an indirect connection between components through other components.

Inspired by the above-mentioned ideal embodiment according to the present invention, through the above-mentioned description content, relevant workers can make various changes and modifications within the scope of not departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification, but must be determined according to the scope of the claims.

Claims (8)

1. A lime-stabilized iron tailings pavement subbase material for urban roads, characterized in that: the subbase material comprises the following components by mass: 100 parts of iron tailings; 5-7 parts of lime; 9-15 parts of water share. 2. the preparation method of a kind of city road according to claim 1 stabilized iron tailings pavement base material with lime, is characterized in that, comprises the following steps: Step S1, after fully mixing the iron tailings and lime weighed according to the mass ratio, carry out a compaction test, and measure the _optimum moisture content MCjia and the maximum dry density _ρmax ; Step S2, measuring the moisture content MC ₀ of the iron tailings, then weighing the iron tailings and lime in proportion, and mixing them evenly to obtain a mixture; Step S3, increase the _optimal moisture content MC by 1-2 percentage points _as the preset moisture content MC of the mixture, calculate the amount of water added and weigh it; Step S4, add 80%-90% of the weighed water into the mixture, seal it with a plastic film after fully stirring, and keep the mixture for more than 12 hours; Step S5, after the stuffing is finished, the remaining water is added to the mixture for secondary mixing to finally obtain the required lime-stabilized iron tailings pavement subbase material for urban roads. 3. A kind of preparation method of lime-stabilized iron tailings pavement subbase material for urban roads according to claim 2, characterized in that: the maximum particle size of the iron tailings is not more than 4.75mm, and the particle size is below 0.075mm The particle mass fraction is greater than 60%, the plasticity index is 17-19, and the organic matter content is less than 5%. 4. a kind of preparation method of urban road according to claim 2 uses lime-stabilized iron tailings pavement subbase material, it is characterized in that: in described iron tailings, each mineral content is dolomite (CaMg(CO ₃ ) ₂ ) 18%-22%, siderite (FeCO ₃ ) 18%-22%, quartz (SiO ₂ ) 15%-16%, calcite (CaCO ₃ ) 12%-13%, hematite (Fe ₂ O ₃ ) 11%-12%, kaolinite (Al ₄ [Si ₄ O ₁₀ ](OH) ₈ ) 9%-10%, muscovite (KAl ₂ [AlSi ₃ 0 ₁₀ ](OH) ₂ ) 8%- 9% and pyrite (FeS ₂ ) 2%-3%. 5. A kind of preparation method of lime-stabilized iron tailings pavement subbase material for urban roads according to claim 2, characterized in that: the leaching concentration of each heavy metal in the iron tailings copper is less than 26.77 μg/L, barium The element is less than 61.61μg/L, the chromium element is less than 2.28μg/L, the cadmium element is less than 2.28μg/L, and the lead element is less than 0.20μg/L. 6 . The method for preparing a lime-stabilized iron tailings pavement subbase material for urban roads according to claim 2 , characterized in that: the type of pavement for which the subbase material is applied is urban road pavement. 7 . 7 . The method for preparing a lime-stabilized iron tailings pavement sub-base material for urban roads according to claim 2 , characterized in that: the layer where the sub-base material is applied is a pavement sub-base. 8. A method for preparing a lime-stabilized iron tailings pavement subbase material for urban roads according to claim 2, characterized in that: the lime in the subbase material is quicklime, and its grade is grade II ash or above.

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